On a network which is structured in a data center, physical resources on the network (a physical server, a physical router, and the like, for example) are shared among multiple tenants. Such a network is referred hereinafter to as a multi-tenant network. The tenant means here a user, such as a company. In the multi-tenant network, filtering is performed by a virtual switch or the like on data transmitted by a virtual machine of some tenant, so that virtual machines of other tenants do not receive the data.
Meanwhile, one mode of transmitting data includes broadcast. The broadcast means that data is transmitted to all nodes in the same layer (L) 2 domain. A related technology discloses that filtering is performed on broadcast on a multi-tenant network as follows. Specifically, when a destination address of a received message is an address of a virtual switch, a computer converts the destination address of the received message to a broadcast address for a virtual machine which is under control of the virtual switch and belongs to the same sub-net. Then, the computer outputs the message after conversion.
However, this technology assumes that an operation of setting a virtual MAC address is performed in advance on a virtual L2 switch which is executed on a computer. The related art is disclosed in, for example, Japanese Laid-open Patent Publication No. 2011-171874.